"There are two ways to log into the PSN network - your web based account on the regional portal, and the console itself to play games online," Boyd told El Reg.

"The Japanese PSN website doesn't appear to have a working login anywhere, and I've checked with friends in Japan who say they cannot currently access the network through their consoles."

Gamers in the rest of the world were greeted with a "Welcome Back" package on rejoining the network, designed to provide compensation for the four weeks without the service. Gamers will be offered a choice of two complimentary titles from a selection of four when the PlayStation Store reopens at the end of May.

The entertainment giant is also offering 30 days' free membership of its PlayStation Plus scheme, or 60 days to existing subscribers. Plus membership offers discounts for game purchase and the ability to save gaming positions to cloud-based servers.

Sony suffered a hack on its PlayStation Network and Online Entertainment service last month that exposed the personal details of 77 million PlayStation Network gamers and (separately) 25 million customers of its Online Entertainment services. The entertainment giant pulled the plug on both services following the incident, which exposed the names, email addresses, dates of birth and phone numbers of PlayStation Network gamers. ®